Explain server-side rendering of React applications and its benefits?

TL;DR

Server-side rendering (SSR) in React involves rendering React components on the server and sending the fully rendered HTML to the client. This approach improves initial load times and SEO. The server handles the initial rendering, and the client takes over with React's hydration process. Benefits include faster initial page loads, better SEO, and improved performance on slower devices.

What is server-side rendering of React applications?

Definition

Server-side rendering (SSR) is a technique where the server renders the initial HTML of a React application and sends it to the client. This is in contrast to client-side rendering (CSR), where the browser downloads a minimal HTML page and renders the content using JavaScript.

How it works

Initial request: When a user requests a page, the server processes this request.
Rendering on the server: The server uses React to render the components into HTML.
Sending HTML to the client: The server sends the fully rendered HTML to the client.
Hydration: Once the HTML is loaded, React takes over and binds the event handlers, making the page interactive.

Code example

Here's a basic example using Next.js, a popular React framework that supports SSR out of the box:

import React from 'react';

const Home = ({ data }) => (
  <div>
    <h1>Welcome to my SSR React App</h1>
    <p>Data from server: {data}</p>
  </div>
);

export async function getServerSideProps() {
  // Fetch data from an API or database
  const data = await fetchDataFromAPI();
  return { props: { data } };
}

export default Home;

Benefits of server-side rendering

Improved initial load time

Faster content display: Since the server sends fully rendered HTML, users see the content faster compared to CSR, where the browser has to download and execute JavaScript before rendering.

Better SEO

Search engine indexing: Search engines can easily index the fully rendered HTML, improving the SEO of your application. This is particularly important for content-heavy sites.

Performance on slower devices

Reduced client-side processing: SSR reduces the amount of JavaScript that needs to be processed on the client side, which is beneficial for users with slower devices or poor network conditions.

Enhanced user experience

Perceived performance: Users perceive the application as faster because they see content sooner, even if the JavaScript is still loading in the background.